Modified heterophasic polyolefin composition

ABSTRACT

A method of creating a modified heterophasic polyolefin composition is provided, whereby a polyolefin composition having at least two phases is melt mixed with a free radical generator, such as a peroxide, and a compatibilizing agent characterized by at least one nitroxide radical and at least one unsaturated bond capable of undergoing a radical addition reaction. Modified heterophasic polyolefin compositions with increased melt flow rates, impact strength, and clarity, which incorporate the compatibilizing agent, are also included within the scope of the invention.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/641,719 filed on Mar. 9, 2015, which application claims, pursuant to35 U.S.C. § 119(e)(1), priority to and the benefit of the filing date ofU.S. Patent Application No. 61/953,261 filed on Mar. 14, 2014, both ofwhich applications are herein incorporated by reference.

TECHNICAL FIELD OF THE INVENTION

The present invention is directed to a heterophasic polyolefincomposition having an increased melt flow rate, as well as high impactstrength and improved clarity. Of particular interest are modifiedpolypropylene impact copolymers.

BACKGROUND OF THE INVENTION

The melt flow rate (MFR) of a polymer resin is a function of itsmolecular weight. In general, increasing the melt flow rate allows theresin to be processed at lower temperatures and to fill complex partgeometries. Various prior art methods of increasing the melt flow rateinvolve melt-blending the resin in an extruder with a compound capableof generating free radicals, such as a peroxide. When this is done, theweight average molecular weight of the polymer is reduced and the MFR isincreased. Increasing the melt flow rate by decreasing the molecularweight of the polyolefin polymer, however, has been found in many casesto have a detrimental effect on the strength of the modified polymer.

Mestanza et al.—U.S. Pat. No. 6,020,437 disclose a method of improvingthe rheological properties of polypropylene polymers by melt-blendingthe polypropylene with (a) a functional compound having at least 2acrylate groups, (b) a thiuram sulfide compound, and (c) a compoundcapable of generating free radicals.

Bertin et al. —U.S. Pat. No. 6,620,892 disclose a method of modifying apolypropylene homopolymer or copolymer resin, to increase the melt flowwhile preserving the strength of the polymer resin, by melt-blending theresin, a stable free radical selected from nitroxyl radicals comprisingat least one=N—O— group, and a peroxide compound (trigger), in theabsence of a functional monomer.

Onoi et al. —U.S. Pat. No. 7,019,086, Ashiura et al. —U.S. Pat. No.7,196,144, and Ashiura et al. —U.S. Pat. No. 7,772,325, all assigned toYokohama Rubber Co., Ltd., disclose methods to modify an elastomer toimprove its bondability, by reacting the elastomer with a compoundcapable of forming a stable free radical, in the presence of a freeradical initiator, such as a peroxide. Examples of such stable freeradical compounds include nitroxide radicals, hydrazyl radicals, aryloxyradicals and trityl radicals.

Caronia et al. —US Publication 2007/0145625 disclose a process forcross-linking a polymer after it has been formed into an article. Thefree-radical crosslinkable polymer is hydrocarbon-based. The freeradical cross-linking agent may be selected from (i) hinderedamine-derived stable organic free radicals, (ii) iniferters, (iii)organometallic compounds, (iv) aryl azooxy radicals, and (v) nitrosocompounds, preferably a bis-TEMPO or 4-hydroxy-TEMPO.

Horst et al. —U.S. Pat. No. 8,618,224 B2 disclose a viscosity breakingprocess for polypropylene, polypropylene copolymers and polypropyleneblends. The vis-breaking of the polymer is conducted, for example, in anextruder, in the presence of an initiator (e.g. peroxide) and a “chaintransfer agent.” Suitable chain transfer agents are thiols, disulfides,phosphorous acid esters, phosphines, organic iodides, organic chlorides,propionic acid esters, aldehydes and tertiary amines.

Pham et al. —EP 1 391 482 B1 disclose a polyolefin compositioncomprising a reactively modified heterophasic copolymer obtained by meltcompounding the heterophasic copolymer with an organic peroxide and abifunctionally unsaturated monomer, such a butadiene.

SUMMARY OF THE INVENTION

Heterophasic polyolefin compositions, such as polypropylene impactcopolymers, provide high impact strength, especially at sub-ambienttemperatures. The heterophasic polyolefin compositions are useful in awide range of industrial and household articles, including automotiveparts, appliances, caps and closures and containers. One drawback ofheterophasic polyolefin compositions, in general, and polypropyleneimpact copolymers, in particular, however, has been their relatively lowmelt flow rate. Conventional methods of increasing the MFR of thepolymers, such as peroxide initiated viscosity breaking techniques,dramatically reduces their impact performance.

It has been discovered that in certain heterophasic polyolefin systemsthe incorporation of a compatibilizing agent characterized by (i) atleast one nitroxide radical or a moiety capable of producing at leastone nitroxide radical while being melt mixed with the heterophasicpolyolefin polymer composition; and (ii) at least one unsaturated bondcapable of undergoing a radical addition reaction, can ameliorate thedetrimental effect on impact strength and in some cases even improve theimpact strength of heterophasic polyolefin polymers, when such polymersare subjected to viscosity breaking techniques.

The polymer compositions of interest typically have a MFR of less than200 g/10 min. With the present invention it is possible to (i) increasethe MFR, while minimizing the decrease in impact strength of the polymercomposition that would normally accompany the increase in MFR and/or(ii) improve the impact strength, while maintaining or increasing theMFR. In certain embodiments of the invention it is possible to bothincrease the MFR and improve the impact strength of the polymercomposition. Additionally, the compatibilizing agents of the subjectinvention have been found to dramatically increase the clarity ofheterophasic polyolefin compositions.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a bar chart showing the change in MFR of a propylene impactcopolymer, with 500 ppm of an organic peroxide, at various loadinglevels of the compatibilizing agent.

FIG. 2 is a bar chart showing the change in MFR of a propylene impactcopolymer, with 1,000 ppm of an organic peroxide, at various loadinglevels of the compatibilizing agent.

FIG. 3 is a bar chart showing the change in Izod Impact Strength (23°C.) of a propylene impact copolymer, with 500 ppm of an organicperoxide, at various loading levels of the compatibilizing agent.

FIG. 4 is a bar chart showing the change in Izod Impact Strength (23°C.) of a propylene impact copolymer, with 1,000 ppm of an organicperoxide, at various loading levels of the compatibilizing agent.

FIG. 5 is a graph of Izod Impact Strength (23° C.) versus MFR of apropylene impact copolymer, in which both Examples 1-6 and ComparativeExamples C1-C6 are plotted.

FIG. 6 is a graph of gel permeation chromatography curves indicating themolecular weight distribution (retention time increases as molecularweight decreases) for the unmodified, heterophasic polyolefin resin, theresin treated with peroxide only, and the modified resins of Examples 1and 2.

FIG. 7 is a graph of gel permeation chromatography curves indicating themolecular weight distribution (retention time increases as molecularweight decreases) for the unmodified, heterophasic polyolefin resin, theresin treated with peroxide only, and the resins of Comparative ExamplesC1 and C2.

FIG. 8 is a graph of gel permeation chromatography curves indicating themolecular weight distribution (retention time increases as molecularweight decreases) for the modified heterophasic resin of Example 2 andthe resin of Comparative Example 2.

FIG. 9 is a graph of gel permeation chromatography curves indicating themolecular weight distribution (retention time increases as molecularweight decreases) for the unmodified, polypropylene (non-heterophasic)polyolefin resin, the resin treated with peroxide only, and the resinsof Comparative Examples C7 and C8.

DETAILED DESCRIPTION OF THE INVENTION

Without limiting the scope of the invention, the preferred embodimentsand features are hereinafter set forth. All of the United Statespatents, which are cited in the specification, are hereby incorporatedby reference. Unless otherwise indicated, conditions are 25° C., 1atmosphere of pressure and 50% relative humidity, concentrations are byweight, molecular weight is based on weight average molecular weight,and aliphatic hydrocarbons and radicals thereof are from one to twelvecarbon atoms in length. The term “polymer” as used in the presentapplication denotes a material having a weight average molecular weight(M_(w)) of at least 5,000. The term “copolymer” is used in its broadsense to include polymers containing two or more different monomerunits, such as terpolymers, and unless otherwise indicated, includesrandom, block, and statistical copolymers. The concentration of ethyleneor propylene in a particular phase or in the heterophasic composition isbased on the weight of reacted ethylene units or propylene unitsrelative to the total weight of polyolefin polymer in the phase orheterophasic composition, respectively, excluding any fillers or othernon-polyolefin additives. The concentration of each phase in the overallheterogeneous polymer composition is based on the total weight ofpolyolefin polymers in the heterophasic composition, excluding anyfillers or other non-polyolefin additives or polymers.

Polymers

The subject heterophasic polyolefin polymers that may be advantageouslymodified according to the present invention are characterized by atleast two distinct phases—a propylene polymer phase comprising propylenepolymers selected from polypropylene homopolymers and copolymers ofpropylene and up to 50 weight % of ethylene and/or C₄-C₁₀ α-olefins andan ethylene polymer phase comprising ethylene polymers selected fromethylene homopolymers and copolymers of ethylene and C3-C₁₀ α-olefins.The ethylene content of the ethylene polymer phase is at least 8 weight%. When the ethylene phase is a copolymer of ethylene and C₃-C₁₀α-olefins, the ethylene content of the ethylene phase may range from 8to 90 weight %. In one embodiment of the invention, the ethylene contentof the ethylene phase is at least 50 weight %. Either the propylenepolymer phase or the ethylene polymer phase may form the continuousphase and the other will form the discrete or dispersed phase. Forexample, the ethylene polymer phase may be the discontinuous phase andthe polypropylene polymer phase may be the continuous phase. In oneembodiment of the invention, the propylene content of the propylenepolymer phase is greater than the propylene content of the ethylenepolymer phase.

The relative concentrations of the propylene polymer phase and theethylene polymer phase may vary over a wide range. By way of example,the ethylene polymer phase may comprise from 5 to 80 weight % of thetotal of propylene polymers and ethylene polymers in the composition andthe propylene polymer phase may comprise from 20 to 95 weight % of thetotal of propylene polymers and ethylene polymers in the composition.

In various embodiments of the invention, (i) the ethylene content mayrange from 5 to 75 weight %, or even 5 to 60 weight %, based on thetotal propylene polymer and ethylene polymer content in the heterophasiccomposition, (ii) the ethylene polymer phase may be anethylene-propylene or ethylene-octene elastomer, and/or (iii) thepropylene content of the propylene polymer phase may be 80 weight % orgreater.

The present invention is particularly useful in modifying polypropyleneimpact copolymers. The impact copolymer may be characterized by acontinuous phase comprising polypropylene polymers selected frompolypropylene homopolymers and copolymers of propylene and up to 50weight % of ethylene and/or C₄-C₁₀ α-olefins and a discontinuous phasecomprising elastomeric ethylene polymers selected from ethylene/C₃-C₁₀α-olefin monomers and the ethylene polymers have an ethylene content offrom 8 to 90 weight %.

In various embodiments of the invention directed to propylene impactcopolymers, (i) the ethylene content of the discontinuous phase may befrom 8 to 80 weight %, (ii) the ethylene content of the heterophasiccomposition may be from 5 to 30 weight %, based on the total propylenepolymers and ethylene polymers in the composition; (iii) the propylenecontent of the continuous phase may be 80 weight % or greater and/or(iv) the discontinuous phase may be from 5 to 35 weight % of the totalpropylene polymers and ethylene polymers in the composition.

Examples of heterophasic polyolefin polymers that may be modified areimpact copolymers characterized by a relatively rigid, polypropylenehomopolymer matrix (continuous phase) and a finely dispersed phase ofethylene-propylene rubber (EPR) particles. Polypropylene impactcopolymer may be made in a two-stage process, where the polypropylenehomopolymer is polymerized first and the ethylene-propylene rubber ispolymerized in a second stage. Alternatively, the impact copolymer maybe made in three or more stages, as is known in the art. Suitableprocesses may be found in the following references: U.S. Pat. Nos.5,639,822 and 7,649,052 B2. Examples of suitable processes to makepolypropylene impact copolymers are Spheripol®, Unipol®, Mitsui process,Novolen process, Spherizone®, Catalloy®, Chisso process, Innovene®,Borstar®, and Sinopec process. These processes could use heterogeneousor homogeneous Ziegler-Natta or metallocene catalysts to accomplish thepolymerization.

The heterophasic polyolefin polymer composition may be formed by meltmixing two or more polymer compositions, which form at least twodistinct phases in the solid state. By way of example, the heterophasicpolyolefin composition may comprise three distinct phases. Theheterophasic polyolefin polymer composition may result from melt mixingtwo or more types of recycled polyolefin compositions. Accordingly, thephrase “providing a heterophasic polyolefin polymer composition” as usedherein includes employing a polyolefin polymer composition in theprocess that is already heterophasic, as well as melt mixing two or morepolyolefin polymer compositions during the process, wherein the two ormore polyolefin polymer compositions form a heterophasic system. Forexample, the heterophasic polyolefin polymer may be made by melt mixinga polypropylene homopolymer and an ethylene/α-olefin copolymer, such asan ethylene/butene elastomer. Examples of suitable copolymers would beEngage™, Exact®, Vistamaxx®, Versify™, INFUSE™, Nordel™, Vistaion®,Exxelor™, and Affinity™. Furthermore, it can be understood that themiscibility of the polyolefin polymer components that form theheterophasic system may vary when the composition is heated above themelting point of the continuous phase in the system, yet the system willform two or more phases when it cools and solidifies. Examples ofheterophasic polyolefin polymer compositions may be found in U.S. Pat.No. 8,207,272 B2 and EP 1 391 482 B1.

In one embodiment of the invention, the heterophasic polyolefin polymerto be modified does not have any polyolefin constituents withunsaturated bonds, in particular, both the propylene polymers in thepropylene phase and the ethylene polymers in the ethylene phase are freeof unsaturated bonds.

In another embodiment of the invention, in addition to the propylenepolymer and ethylene polymer components, the heterophasic system mayinclude an elastomer, such as elastomeric ethylene copolymers,elastomeric propylene copolymers, styrene block copolymers, such asstyrene-butadiene-styrene (SBS), styrene-ethylene-butylene-styrene(SEBS), styrene-ethylene-propylene-styrene (SEPS) andstyrene-isoprene-styrene (SIS), plastomers, ethylene-propylene-dieneterpolymers, LLDPE, LDPE, VLDPE, polybutadiene, polyisoprene, naturalrubber, and amorphous polyolefins. The rubbers may be virgin orrecycled.

Method of Processing to Form the Modified Composition

The heterophasic polyolefin polymer composition is modified by mixingthe polymer composition with a compatibilizing agent in the presence offree radicals, which have been generated in the composition.

In one embodiment of the invention, the heterophasic polyolefin polymercomposition is modified by melt mixing the polymer composition with acompatibilizing agent in the presence of free radicals, which have beengenerated in the composition. The melt mixing step is conducted underconditions such that the composition is heated to above the meltingtemperature of the major polyolefin component of the composition andmixed while in the molten state. Examples of suitable melt mixingprocesses include melt compounding, such as in an extruder, injectionmolding, and mixing in a Banbury mixer or kneader. By way of example,the mixture may be melt mixed at a temperature of from 160° C. to 300°C. In particular, propylene impact copolymers may be melt mixed at atemperature of from 180° C. to 290° C. The polymer composition(propylene polymer phase and ethylene polymer phase), compatibilizingagent and an organic peroxide may be melt compounded in an extruder, ata temperature above the melting temperature of all of the polyolefinpolymers in the composition.

In another embodiment of the invention, the polymer may be dissolved ina solvent and the compatibilizing agent added to the polymer solution,and the radicals generated in solution. In another embodiment of theinvention, the compatibilizing agent may be combined with the polymer inthe solids state and free radicals could be generated during solid-stateshear pulverization as described in Macromolecules, “EsterFunctionalization of Polypropylene via Controlled Decomposition ofBenzoyl Peroxide during Solid-State Shear Pulverization”—vol. 46, pp.7834-7844 (2013).

Conventional processing equipment may be used to mix the propylenepolymers, ethylene polymers and compatibilizing agent together in asingle step, in the presence of free radicals that are either added tothe mixture, such as an organic peroxide, or generated in-situ, such asby shear, UV light, etc. Nevertheless, it is also possible to mixvarious combinations of the components in multiple steps and in varioussequences, and subsequently subject the mixture to conditions wherebythe compatibilizing agent reacts with the polyolefin polymers, asdescribed herein.

For example, the compatibilizing agent and/or the free radical generator(when a chemical compound is used) can be added to the polymer in theform of one or masterbatch compositions. Suitable masterbatchcompositions can comprise the compatibilizing agent and/or the freeradical generator in a carrier resin. The compatibilizing agent and/orthe free radical generator can be present in the masterbatch compositionin an amount of about 1 wt. % to about 80 wt. % based on the totalweight of the composition. Any suitable carrier resin can be used in themasterbatch compositions, such as any suitable thermoplastic polymer.For example, the carrier resin for the masterbatch compositions can be apolyolefin polymer, such as a polypropylene impact copolymer, apolyethylene homopolymer, a linear low density polyethylene polymer, apolyolefin wax, or mixtures of such polymers. The carrier resin can alsobe a propylene polymer or an ethylene polymer that is the same as orsimilar to the proplylene polymer or ethylene polymer present in theheterophasic polyolefin polymer composition. Such a masterbatchcomposition would allow the end user to manipulate the ratio ofpropylene polymer(s) to ethylene polymer(s) present in the heterophasicpolyolefin polymer composition. This may be preferred when the end userneeds to modify the propylene to ethylene ratio of a commercial resingrade in order to achieve the desired set of properties (e.g., balanceof impact and stiffness).

Compatibilizing Agents

The compatibilizing agent is an organic compound characterized by (i) atleast one nitroxide radical or a moiety capable of producing at leastone nitroxide radical while being melt mixed with the heterophasicpolyolefin polymer composition; and (ii) at least one unsaturated bondcapable of undergoing a radical addition reaction. Of particular utilityare compatibilizing agents having an unsaturated carbon-carbon bond,such as a double bond.

It is believed that in the presence of a free radical, the nitroxideradical functionality of the compatibilizing agent and the unsaturatedbond functionality react with and bond to the propylene polymers and theethylene polymers present in the composition. Thus, in accordance withthe method of the present invention, it is possible to provide amodified composition comprising propylene polymers bonded to ethylenepolymers by the compatibilizing agent. In particular, it is believedthat the nitroxide radical functionality preferentially reacts with andbonds to the propylene polymers in the composition, and the unsaturatedbond functionality preferentially reacts with and bonds to the ethylenepolymers in the composition. The modification accounts for the highermolecular weight components, i.e. higher than the unmodified or peroxideonly modified heterophasic polyolefin composition, which have beenobserved when the subject compatibilizing agent is provided in themixture. The resulting structure compensates for the downward shift inaverage molecular weight caused by the breaking of polymer chains, asthe MFR is modified. Additionally, the presence of higher molecularweight species in the composition, comprising polypropylene polymers andethylene polymers bonded together by the compatibilizing agent, isbelieved to affect the interface between the phases in the heterophasiccomposition, thereby dramatically improving the optical properties, asmeasured by clarity.

Examples of nitroxide compounds that may be used in the presentinvention, provided that the compounds are synthesized or modified tocontain at least one unsaturated bond capable of undergoing a radicaladdition reaction, may be found in Synthetic Chemistry of StableNitroxides, L. B. Volodarsky et al. CRC Press, Inc. (1994). Thenitroxide compound may be a 5- or 6-membered heterocyclic compound,which may incorporate the nitroxide nitrogen in the ring structure. Forexample, the compatibilizing agent may be based on2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO), such as:

wherein R is selected from unsaturated groups capable of undergoingfree-radical addition, for example an aliphatic alkenyl group or alkenylsubstituted aromatic group, such as phenyl. In particular, the alkenylgroup may be from C₁ to C₁₀, more preferably C₁ to C₈, C₁ to C₆, or C₁to C₄. Specific compounds useful in the present invention are4-Methacryloyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl,(“TEMPO-Methacrylate”),4-Acryloyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl (“TEMPO-Acrylate”),4-((4-vinylbenzyl)oxy)-2,2,6,6-tetramethylpiperidine-1-oxyl(“TEMPO-Styrene”),4,4′-((bicyclo[2.2.1]hept-5-ene-2,3-diylbis(oxy))bis(2,2,6,6-tetramethylpiperidin-1-oxyl)(“Norbornene”), and N-tert-Butyl-α-phenylnitrone (“Nitrone”).

The concentration of the compatibilizing agent in the composition can bevaried to meet the objectives of the end user. For example, theconcentration can be varied in order to achieve a desired increase inthe MFR of the polymer composition with a minimal decrease (orpotentially even an increase) in the strength of the polymer, inparticular the impact strength. In a preferred embodiment, thecompatibilizing agent can be present in an amount of about 10 ppm ormore, about 50 ppm or more, about 100 ppm or more, about 150 ppm ormore, or about 200 ppm or more, based on the total weight of the polymercomposition. In another preferred embodiment, the compatibilizing agentcan be present in an amount of about 5 wt. % (50,000 ppm) or less, about4 wt. % (40,000 ppm) or less, about 3 wt. % (30,000 ppm) or less, about2 wt. % (20,000 ppm) or less, about 1 wt. % (10,000 ppm) or less, orabout 0.5 wt. % (5,000 ppm) or less, based on the total weight of thepolymer composition. Thus, in certain preferred embodiments, thecompatibilizing agent can be present in an amount of about 10 to about50,000 ppm, about 100 to about 10,000 ppm, or about 200 to about 5,000ppm, based on the total weight of the polymer composition.

When a chemical free radical generator is employed (as discussed below),the concentration of the compatibilizing agent in the polymercomposition can additionally or alternatively be expressed in terms of aratio between the amount of the compatibilizing agent and the amount ofthe chemical free radical generator. In order to normalize this ratiofor differences in the molecular weight of compatibilizing agents andnumber of peroxide bonds in the chemical free radical generators, theratio is usual expressed as a ratio of the number of moles ofcompatibilizing agent present in the composition to the molarequivalents of peroxide bonds (0-0 bonds) present from the addition ofthe chemical free radical generator. Preferably, the ratio (i.e., ratioof moles of compatibilzing agent to molar equivalents of peroxide bonds)is about 1:10 or more, about 1:5 or more, about 3:10 or more, about 2:5or more, about 1:2 or more, about 3:5 or more, about 7:10 or more, about4:5 or more, about 9:10 or more, or about 1:1 or more. In anotherpreferred embodiment, the ratio is about 10:1 or less, about 5:1 orless, about 10:3 or less, about 5:2 or less, about 2:1 or less, about5:3 or less, about 10:7 or less, about 5:4 or less, about 10:9 or less,or about 1:1 or less. Thus, in a series of preferred embodiments, thecompatibilizing agent can be present in the composition in a ratio ofmoles of compatibilizing agent to molar equivalents of peroxide bonds ofabout 1:10 to about 10:1, about 1:5 to about 5:1, about 1:4 to about4:1, about 3:10 to about 10:3, about 2:5 to about 5:2, or about 1:2 toabout 2:1.

Free Radical Generator

A free radical generator is employed in the present invention to causepolymer chain scission and thereby positively affect the MFR of theheterophasic polyolefin polymer composition, while generating sufficientfree radicals to foster the reaction of the compatibilizing agent withthe polyolefin polymers in the composition. The free radical generatormay be a chemical compound, such as an organic peroxide or a bis-azocompound, or free radicals may be generated by applying ultrasound,shear, an electron beam (for example β-rays), light (for example UVlight), heat and radiation (for example γ-rays and X-rays), to thereaction system, or combinations of the foregoing.

Organic peroxides having one or more 0-0 functionalities are ofparticular utility in the present invention. Examples of such organicperoxides include: 2,5-dimethyl-2,5-di(t-butylperoxy)hexane,2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3,3,6,6,9,9-pentamethyl-3-(ethyl acetate)-1,2,4,5-tetraoxycyclononane, t-butyl hydroperoxide, hydrogen peroxide, dicumyl peroxide,t-butyl peroxy isopropyl carbonate, di-t-butyl peroxide, p-chlorobenzoylperoxide, dibenzoyl diperoxide, t-butyl cumyl peroxide; t-butylhydroxyethyl peroxide, di-t-amyl peroxide and2,5-dimethylhexene-2,5-diperisononanoate, acetylcyclohexanesulphonylperoxide, diisopropyl peroxydicarbonate, tert-amyl perneodecanoate,tert-butyl-perneodecanoate, tert-butylperpivalate, tert-amylperpivalate,bis(2,4-dichlorobenzoyl)peroxide, diisononanoyl peroxide, didecanoylperoxide, dioctanoyl peroxide, dilauroyl peroxide,bis(2-methylbenzoyl)peroxide, disuccinoyl peroxide, diacetyl peroxide,dibenzoyl peroxide, tert-butyl per-2-ethylhexanoate,bis(4-chlorobenzoyl)peroxide, tert-butyl perisobutyrate, tert-butylpermaleate, 1,1-bis(tert-butylperoxy)-3,5,5-trimethylcyclo-hexane,1,1-bis(tert-butylperoxy)cyclohexane, tert-butyl peroxyisopropylcarbonate, tert-butyl perisononaoate, 2,5-dimethylhexane 2,5-dibenzoate,tert-butyl peracetate, tert-amyl perbenzoate, tert-butyl perbenzoate,2,2-bis(tert-butylperoxy)butane, 2,2-bis(tert-butylperoxy)propane,dicumyl peroxide, 2,5-dimethylhexane 2,5-di-tert-butylperoxid,3-tert-butylperoxy-3-phenyl phthalide, di-tert-amyl peroxide,α,α′-bis(tert-butylperoxyisopropyl)benzene,3,5-bis(tert-butylperoxy)-3,5-dimethyl-1,2-dioxolane, di-tert-butylperoxide, 2,5-dimethylhexyne 2,5-di-tert-butyl peroxide,3,3,6,6,9,9-hexamethyl-1,2,4,5-tetraoxacyclononane, p-menthanehydroperoxide, pinane hydroperoxide, diisopropylbenzenemono-α-hydroperoxide, cumene hydroperoxide or tert-butyl hydroperoxide.

The organic peroxide can be present in the polymer composition in anysuitable amount. The suitable amount of organic peroxide will dependupon several factors, such as the particular polymer that is used in thecomposition, the starting MFR of the polymer, and the desired change inthe MFR of the polymer. In a preferred embodiment, the organic peroxidecan be present in the polymer composition in an amount of about 10 ppmor more, about 50 ppm or more, or about 100 ppm or more, based on thetotal weight of the polymer composition. In another preferredembodiment, the organic peroxide can be present in the polymercomposition in an amount of about 2 wt. % (20,000 ppm) or less, about 1wt. % (10,000 ppm) or less, about 0.5 wt. % (5,000 ppm) or less, about0.4 wt. % (4,000 ppm) or less, about 0.3 wt. % (3,000 ppm) or less,about 0.2 wt. % (2,000 ppm) or less, or about 0.1 wt. % (1,000 ppm) orless, based on the total weight of the polymer composition. Thus, in aseries of preferred embodiments, the organic peroxide can be present inthe polymer composition in an amount of about 10 to about 20,000 ppm,about 50 to about 5,000 ppm, about 100 to about 2,000 ppm, or about 100to about 1,000 ppm, based on the total weight of the polymercomposition. The amount of organic peroxide can also be expressed interms of a molar ratio of the compatibilizing agent and peroxide bonds,as is described above.

Suitable bis azo compounds may also be employed as a source of freeradicals. Such azo compounds are for example2,2′-azobisisobutyronitrile, 2,2′-azobis(2-methylbutyronitrile),2,2′-azobis(2,4-dimethylvaleronitrile),2,2′-azobis(4-methoxy-2,4-dimethylvaleronitrile),1,1′-azobis(1-cyclohexanecarbonitrile),2,2′-azobis(isobutyramide)dihydrate,2-phenylazo-2,4-dimethyl-4-methoxyvaleronitrile, dimethyl2,2′-azobisisobutyrate, 2-(carbamoylazo)isobutyronitrile,2,2′-azobis(2,4,4-trimethylpentane), 2,2′-azobis(2-methyl-propane),2,2′-azobis(N,N′-dimethyleneisobutyramidine) as free base orhydrochloride, 2,2′-azobis(2-amidinopropane) as free base orhydrochloride,2,2′-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)ethyl]propionamide} or2,2′-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide}.

Other chemical compounds useful as free radical initiators include2,3-dimethyl-2,3-diphenylbutane and sterically hindered hydroxylamineester.

The various radical generators may be employed alone or in combination.

Additives

The heterophasic polyolefin composition of the present invention iscompatible with various types of additives conventionally used inthermoplastic compositions, including stabilizers, UV absorbers,hindered-amine light stabilizers (HALS), antioxidants, flame retardants,acid neutralizers, slip agents, antiblocking agents, antistatic agents,antiscratch agents, processing aids, blowing agents, colorants,opacifiers, clarifiers, and/or nucleating agents. By way of furtherexample, the composition may comprise fillers, such as calciumcarbonate, talc, glass fibers, glass spheres, inorganic whiskers such asHyperform® HPR-803i available from Milliken Chemical, USA, magnesiumoxysulfate whiskers, calcium sulfate whiskers, calcium carbonatewhiskers, mica, wollastonite, clays, such as montmorillonite, andbio-sourced or natural filler. The additives may comprise up to 75weight % of the total components in the modified heterophasic polyolefincomposition.

EXAMPLES

The following examples further illustrate the subject matter describedabove but, of course, should not be construed as in any way limiting thescope thereof. The following methods, unless noted, were used todetermine the properties described in the following examples.

Each of the compositions was compounded by blending the components in aclosed container for approximately one minute. The compositions werethen melt compounded on a Prism TSE-16-TC co-rotating, fullyintermeshing, parallel, twin-screw extruder with a 16 mm screw diameterand a length/diameter ratio of 25:1. The barrel temperature of theextruder was ramped from approximately 195° C. to approximately 215° C.,and the screw speed was set at approximately 500 rpm. The extrudate (inthe form of a strand) for each polypropylene copolymer composition wascooled in a water bath and subsequently pelletized.

The pelletized compositions were then used to form bars by injectionmolding the compositions on a Nissei HM7 7 ton injection molder having a14 mm diameter screw. The barrel temperature of the injection molder wasapproximately 215 to 230° C., and the mold temperature was approximately25° C. The resulting bars measured approximately 80 mm long,approximately 10 mm wide, and approximately 4.0 mm thick.

The melt flow rate (MFR) was determined on the pelletized compositionsaccording to (ASTM D1238) at 230° C. with a load of 2.16 kg forpolypropylene.

The notched Izod impact strength for the bars was measured according toISO method 180/A. The notched Izod impact strength was measured at +23°C. on bars that had been conditioned at either +23° C. or −30° C.

The molecular weight distribution (MWD) as well as the weight average ofsaid distribution, M_(w), was determined using gel permeationchromatography (GPC), also referred to as size exclusion chromatography(SEC). All measurements were conducted by the use of the Agilent PL-GPC220 GPC/SEC system containing (3) 300×7.5 mm PLgel 10 μm Mixed-B LScolumns, a Refractive Index detector, Viscometer and 15° and 90° LightScattering detector (at 160° C.) with trichlorobenzene inhibited with125 ppm butylhydroxytoluene as mobile phase, a column temperature of160° C. and a sample concentration of approx. 1 mg/ml. In the exampleslisted below, a 15° light scattering detector is chosen to measureconcentration. Gel permeation chromatography is a separation techniquein which molecules are separated on the basis of hydrodynamic molecularvolume or size. With proper column calibration or by the use ofmolecular-weight-sensitive detectors, such as light scattering orviscometry, the molecular weight distribution and the statisticalmolecular weight averages can be obtained. In gel permeationchromatography, molecules pass through a column via a combination oftransport into and through beads along with between beads in the column.The time required for passage of a molecule through the column isdecreased with increasing molecular weight. The amount of polymerexiting the column at any given time is measured with various detectors.A more in depth description of the instrumentation and detectors can befound in the chapter titled “Composition, Molar Mass and Molar MassDistribution” in Characterization and Analysis of Polymers by RonClavier (2008).

Xylene solubles were determined by a modified ASTM D5492-10 and are ameasure of the amount of rubber present in the heterophasicpolypropylene copolymers. Approximately 0.6 g of polymer was weighed outand placed into a round-bottom flask along with a stir bar. 50 mL ofxylene was added to the polymer in the flask. The polymer xylene mixturewas heated to reflux temperature while vigorously stirring. Once thereflux temperature was reached, the solution was stirred for anadditional 30 min then cooled to room temperature. The resultingpolymer/xylene mixture was gently stirred to break up any precipitatedpolymer gel then poured through a No. 4 filter paper, both the filtratecontaining the soluble fraction and the insoluble fraction werecollected. A 10 mL aliquot of the filtrate was taken with a Class Apipet and transferred into a weighed pan. The pan containing thefiltrate was then placed on a temperature-controlled hot platemaintaining a temperature of 155° C. to evaporate the xylene. Once mostof the xylene was evaporated, the pan was transferred to a vacuum ovenset at a temperature of 80±10° C. The pressure was reduced to less than13.3 kPa and the sample was dried for approximately 2 hours or until aconstant weight was achieved. The pan mass was then subtracted givingthe mass of the residual soluble polymer. The percentage of solublepolymer in the original sample was calculated as follows:S_(s)=((V_(bo)/ν_(b1)*(W₂−W₁))/W₀)*100; Where: S_(s)=soluble fraction ofsample, %; N_(bo)=original volume of solvent, mL; V_(b1)=volume ofaliquot used for soluble determination, mL; W₂=mass of pan and soluble,g; W₁=mass of pan, g; and W_(o)=mass of original sample, g.

Examples 1-6

The following examples demonstrate the modification of a heterophasicpolyolefin composition and performance enhancements achieved, accordingto the method of the present invention.

The compatibilizing agent was melt compounded into batches of aheterophasic polypropylene copolymer in accordance with the generalformulation set forth in Table 1.

TABLE 1 Heterophasic polypropylene copolymer formulations ComponentLoading Polypropylene copolymer (LyondellBasell Balance Pro-Fax SD375Swith approximately 19% xylene solubles) Primary antioxidant (Irganox ®1010) 500 ppm Secondary antioxidant (Irgafos ® 168) 1000 ppm Acidscavenger (calcium stearate) 800 ppm Peroxide (Varox DBPH) See Table 2Additive (Compatibilizing Agent) See Table 2 Irganox ® 1010 is availablefrom BASF Irgafos ® 168 is available from BASF Varox DBPH is an organicperoxide available from R. T. Vanderbilt Company

Each of the compositions listed in Table 2 was mixed, extruded, andinjection molded according to the above procedure. The bars were thensubjected to melt flow rate and Izod impact testing described above, andevaluated using the 15° light scattering detector signal during testingby Gel Permeation Chromatography (GPC).

TABLE 2 Performance in medium-impact, heterophasic polypropylenecopolymer. Additive Peroxide Loading Additive RT Loading (Molar ratioLoading MFR Izod Sample Additive (ppm) O—O:Additive) (ppm) (g/10 min)(J/m) Unmodified 17 97 Resin Peroxide Only 500 53 52 Ex. 1 TEMPO- 5003:1 276 39 86 Methacrylate Ex. 2 TEMPO- 500 2:1 414 33 100 MethacrylateEx. 3 TEMPO- 500 1:1 827 23 113 Methacrylate Peroxide Only 1000 87 39Ex. 4 TEMPO- 1000 3:1 552 59 78 Methacrylate Ex. 5 TEMPO- 1000 2:1 82744 94 Methacrylate Ex. 6 TEMPO- 1000 1:1 1655 28 115 Methacrylate

Referring to FIG. 1, the MFR data from Table 2 for the unmodified resin,the resin with 500 ppm of the organic peroxide only and three loadinglevels of the compatibilizing agent (Examples 1-3) are presented in barchart format. Referring to FIG. 2, the MFR data from Table 2 for theunmodified resin, the resin with 1,000 ppm of the organic peroxide onlyand three loading levels of the compatibilizing agent (Examples 4-6) arepresented in bar chart format.

Referring to FIG. 3, the Izod Impact Strength (23° C.) data from Table 2for the unmodified resin, the resin with 500 ppm of the organic peroxideonly and three loading levels of the compatibilizing agent (Examples1-3) are presented in bar chart format. Referring to FIG. 4, the IzodImpact Strength (23° C.) data from Table 2 for the unmodified resin, theresin with 1,000 ppm of the organic peroxide only and three loadinglevels of the compatibilizing agent (Examples 4-6) are presented in barchart format.

Comparative Examples C1-C6

The following comparative examples demonstrate the modification of aheterophasic polyolefin composition employing a nitroxide compound,which does not have an unsaturated bond capable of undergoing a radicaladdition reaction.

The nitroxide was melt compounded into batches of a heterophasicpolypropylene copolymer in accordance with the general formulation setforth in Table 1, except that molar equivalents of 4-hydroxy-TEMPO wassubstituted for the compatibilizing agent, namely TEMPO-methacrylate.Each of the compositions listed in Table 3 was mixed, extruded, andinjection molded according to the above procedure. The bars were thensubjected to melt flow rate and Izod impact testing described above, andevaluated using the 15° light scattering detector signal during testingby Gel Permeation Chromatography (GPC).

TABLE 3 Performance in medium impact, heterophasic propylene copolymerAdditive Peroxide Loading Additive RT Loading (Molar ratio Loading MFRIzod Sample Additive (ppm) O—O:Additive) (ppm) (g/10 min) (J/m)Unmodified 17 97 Resin Peroxide Only 500 53 52 Comp. C1 4-Hydroxy- 5003:1 198 38 67 TEMPO Comp. C2 4-Hydroxy- 500 2:1 297 34 69 TEMPO Comp C34-Hydroxy- 500 1:1 593 26 88 TEMPO Peroxide Only 1000 87 39 Comp. C44-Hydroxy- 1000 3:1 395 56 51 TEMPO Comp. C5 4-Hydroxy- 1000 2:1 593 4766 TEMPO Comp. C6 4-Hydroxy- 1000 1:1 1186 27 87 TEMPO

The results obtained for Examples 1-6 and Comparative Examples C1-C6 aregraphed together in FIG. 5, showing the change in Izod Impact Strength(23° C.) versus MFR for each of the compositions, as well as theunmodified resin and the resin containing 500 ppm and 1,000 ppm peroxideonly. The comparative examples containing 4-hydroxy-TEMPO and theinventive examples containing TEMPO-methacrylate have similar melt flowrates when added at equal molar loadings. (See Ex. 1 vs. Comp. Ex. C1;Ex. 2 vs. Comp. C2; Ex. 3 vs. Comp. C3; Ex. 4 vs. Comp. C4; Ex. 5 vs.Comp. C5; and Ex. 6 vs. Comp. C6). When similar comparisons are made forIzod Impact Strength, however, the inventive examples have surprisinglyhigher impact strength when added at equal loadings.

As can be seen in FIG. 5, when the combined properties of MFR and IzodImpact Strength are taken into account, the compatibilizing agent of thepresent invention allows production of modified heterophasic polyolefinresins that occupy a distinct area on the graph from nitroxide compoundsthat do not include an unsaturated bond capable of undergoing a radicaladdition reaction. In fact, as shown in FIGS. 3-5, the method of thepresent invention makes it possible to provide a modified heterophasicpolyolefin resin that has both improved MFR and improved Izod ImpactStrength, relative to the unmodified resin.

The resulting change in polymer molecular weight is shown in FIG. 6,based on GPC data for the unmodified resin, resin mixed with 500 ppm oforganic peroxide only and Examples 1 and 2. When peroxide is added topolypropylene, the molecular weight is decreased as indicated by thepeak shift to longer retention times and there is a relative decrease insignal at retention times less than about 16 minutes. The inventivecompositions show a shift back to shorter retention times (highermolecular weights) and a pronounced shoulder at a retention time ofabout 15 minutes, not observed in the unmodified or peroxide modifiedheterophasic resin. This shoulder indicates the formation of a modifiedpolymer with molecular weight higher than that of either the unmodifiedor peroxide modified heterophasic resin. Referring to FIG. 7, the GPCdata for Comparative Examples C1 and C2 are shown, along with the datafor the unmodified resin and the resin with 500 ppm of organic peroxideonly. When peroxide is added to the heterophasic impact polypropylenecopolymer, the molecular weight is decreased, as indicated by the shiftto longer retention times. The comparative compositions containing4-hydroxy-TEMPO show a shift back to shorter retention times (highermolecular weights) as they counteract the peroxide but do not show theshoulder as seen with Examples 1 and 2.

FIG. 8 shows a direct comparison of inventive Example 2(TEMPO-methacrylate) and Comparative Example C2 (4-hydroxy-TEMPO), whichcontain equal loadings of the peroxide and equal molar loadings of theTEMPO derivatives. The difference in the resulting polymer structure forthe inventive and comparative compositions is evident. This exampleshows the necessity of the unsaturated bond capable of undergoing aradical addition reaction in the nitroxide based compatibilizing agentof the present invention, in order to obtain a molecular weight increaserelative to the unmodified or peroxide only modified heterophasicpolypropylene copolymer.

Comparative Examples C7-C8

The following examples demonstrate the combination of a compatibilizingagent meeting the specifications of the present invention(TEMPO-methacrylate), with a polypropylene homopolymer composition,which is a non-heterophasic polyolefin composition, and thereforeoutside of the scope of the present invention.

The comparative compounds were compounded into batches of polypropylenehomopolymer compositions in accordance with the general formulation setforth in Table 4.

TABLE 4 Polypropylene homopolymer compositions. Component LoadingPolypropylene homopolymer (LyondellBasell Balance Pro-Fax HP6301)Primary antioxidant (Irganox ® 1010) 500 ppm Secondary antioxidant(Irgafos ® 168) 1000 ppm Acid scavenger (calcium stearate) 800 ppmPeroxide (Varox DBPH) 500 ppm Additive (Compatibilizing Agent) See Table5 Irganox ® 1010 is available from BASF Irgafos ® 168 is available fromBASF Varox DBPH is available from R. T. Vanderbilt Company

Each of the polypropylene homopolymer compositions shown in Table 5 wasmixed, extruded, and pelletized according to the above procedure. Thepellets were then subjected to melt flow rate and evaluated using the15° light scattering detector signal during testing by Gel PermeationChromatography (GPC).

TABLE 5 Performance in homopolymer polypropylene. Additive LoadingPeroxide (Molar ratio Additive MFR Loading O—O:Addi- Loading (g/10Sample Additive (ppm) tive) (ppm) min) Unmodified 19 Resin Peroxide 50072 Only Comp. C7 TEMPO- 500 3:1 276 34 Methacrylate Comp. C8 TEMPO- 5002:1 414 27 Methacrylate

The resulting change in polymer molecular weight is shown in FIG. 9 forComparative Examples C7-C8, along with the unmodified non-heterophasicpolypropylene homopolymer resin and the resin with 500 ppm organicperoxide only. When peroxide is added to polypropylene homopolymer, themolecular weight is decreased as indicated by the shift to longerretention times. The comparative compositions containingTEMPO-methacrylate show a shift back to shorter retention times (highermolecular weights), as the TEMPO-methacrylate counteracts the peroxide,but do not show the shoulder as seen with Examples 1 and 2, thusdemonstrating the necessity of the heterophasic nature of thepolypropylene, to achieve the objectives of the present invention.

Examples 7-16 and Comparative Examples C9-C12

The following examples demonstrate the production of compositions andperformance enhancements achieved through the incorporation of nitroxidecompounds having an unsaturated bond capable of undergoing a radicaladdition reaction relative to nitroxide compounds that do not have anunsaturated bond. The inventive and comparative compounds were meltmixed into batches of heterophasic polypropylene copolymer compositions,in accordance with the general formulation set forth in Table 6 and theresults are shown in Table 7.

TABLE 6 Polypropylene copolymer formulations Component LoadingPolypropylene copolymer (LyondellBasell Balance Pro-Fax SD375S withapproximately 19% xylene solubles) Primary antioxidant (Irganox ® 1010)500 ppm Secondary antioxidant (Irgafos ® 168) 1000 ppm Acid scavenger(calcium stearate) 800 ppm Peroxide (Varox DBPH) See Table 7 AdditiveSee Table 7 Irganox ® 1010 is available from BASF Irgafos ® 168 isavailable from BASF Varox DBPH is available from R. T. VanderbiltCompany

Each of the heterophasic polypropylene copolymer compositions was mixed,extruded, and injection molded according to the above procedure. Thebars were then subjected to melt flow rate and Izod impact testingdescribed above. The data for the inventive examples and comparativeexamples are set forth in Table 7.

TABLE 7 Inventive and comparative performance Additive Loading (Molarratio Change in Change in Izod Peroxide O—O Additive Melt Flow Change inIzod impact at Loading Bonds: Loading Rate impact at 23° C. −30° C.Sample Structure (ppm) Additive) (ppm) (%) (%) (%) Unmodified — 0 — — 00 0 Resin Peroxide — 500 — — 211 −38 −14 Only Peroxide — 1000 — — 414−47 −15 Only Ex. 7

1000 2:1 820 225 −1 9 Ex. 8

1000 1:1 1660 72 28 11 Ex. 9

500 2:1 390 88 12 −3 Ex. 10

500 1:1 750 47 24 −2 Ex. 11

1000 2:1 992 157 10 −6 Ex. 12

1000 1:1 1984 69 Non-Break 5 Ex. 13

1000 2:1 1688 158 −3 7 Ex. 14

1000 1:1 3380 48 49 18 Ex. 15

1000 2:1 612 391 −33 −32 Ex. 16

1000 1:1 1220 313 −17 −19 Comp. C9

1000 2:1 593 182.3 −30.4 −29.0 Comp. C10

1000 1:1 1186 61.1 −8.4 −4.6 Comp. C11

500 2:1 320 114 −20 10 Comp. C12

500 1:1 620 28 −5 −4

Comparative Examples C13-C24

The following comparative examples demonstrate the modification of anon-heterophasic ethylene/propylene copolymer resin with (a) nitroxidecompounds having an unsaturated bond capable of undergoing a radicaladdition reaction (compatibilizing agents of the present invention); or(b) nitroxide compounds that do not have an unsaturated bond.

An 11 dg/min melt flow rate ethylene/propylene random copolymerpolypropylene having an ethylene content of about 4.0% and marketedunder the name Pro-Fax SA849S by LyondellBasell Industries was used asthe base resin in the formulation as described in Table 8, below. Thepolyolefin composition is not heterophasic.

TABLE 8 Component Loading Polypropylene random copolymer Balance(LyondellBasell Pro-Fax SA849S) Primary antioxidant (Irganox ® 1010) 500ppm Secondary antioxidant (Irgafos ® 168) 1000 ppm Acid scavenger(calcium stearate) 800 ppm Peroxide (Varox DBPH) 500 ppm Additive(Compatibilizing Agent) See Table 9 Irganox ® 1010 is available fromBASF Irgafos ® 168 is available from BASF Varox DBPH is available fromR. T. Vanderbilt Company

Each of the polypropylene copolymer compositions was mixed, extruded,and injection molded according to the above procedure. The bars werethen subjected to melt flow rate and Izod impact testing describedabove. The resulting changes in melt flow rate and 23° C. Izod impactare listed in Table 9, and show clearly that absent a heterophasicpolypropylene system, there is no benefit of the inventivecompatibilizing agent (Comparative Examples C13-C18) over the othernitroxide compounds that do not have an unsaturated bond (ComparativeExamples C19-C24) in this non-heterophasic resin type, despite theethylene content of the resin.

TABLE 9 Compatibilizing Agent and Nitroxides with a saturated bond in anon-heterophasic polyolefin Additive Change in Change in PeroxideLoading Additive Melt Flow Izod impact Loading (Molar ratio Loading Rateat 23° C. Sample Additive (ppm) O—O:Additive) (ppm) (%) (%) Unmodified 00 0.0 0.0 Resin Peroxide 500 0 315.1 −16.8 Only Comp. C13 TEMPO- 500 3:1276 114.0 −5.5 MA Comp. C14 TEMPO- 500 2:1 414 81.3 −5.5 MA Comp. C15TEMPO- 500 1:1 827 12.5 1.7 MA Peroxide 1000 0 645.1 −20.9 Only Comp.C16 TEMPO- 1000 3:1 552 279.0 −10.3 MA Comp. C17 TEMPO- 1000 2:1 827183.2 −12.9 MA Comp. C18 TEMPO- 1000 1:1 1655 39.9 2.4 MA Comp. C194HOTEMPO 500 3:1 198 143.6 −8.0 Comp. C20 4HOTEMPO 500 2:1 297 128.2−1.8 Comp. C21 4HOTEMPO 500 1:1 593 40.5 −5.4 Comp. C22 4HOTEMPO 10003:1 395 316.2 −23.0 Comp. C23 4HOTEMPO 1000 2:1 593 163.2 0.0 Comp. C244HOTEMPO 1000 1:1 1186 31.7 6.7

Example 17

The following examples demonstrate the production of a modifiedheterophasic polyolefin composition, created by melt mixing apolypropylene homopolymer, a polyolefin elastomer, an organic peroxideand the compatibilizing agent of the present invention. In particular, a2 dg/min polypropylene homopolymer (Total Petrochemicals 3276), 20 w/w %of a polyolefin elastomer (Engage™ 7467 from The Dow Chemical Company),an organic peroxide (Varox DBPH available from R.T. Vanderbilt Company)and TEMPO-methacrylate (Sigma-Aldrich) were melt mixed and tested. Theresults were compared to the heterophasic polyolefin composition createdwhen peroxide only was present and when neither the peroxide nor thecompatibilizing agent were present.

The loadings of the initiator and TEMPO methacrylate are listed in Table10. Each of the polymer blend compositions was mixed, extruded, andinjection molded according to the above procedure. The bars were thensubjected to melt flow rate and Izod impact testing described above.

TABLE 10 Heterophasic polyolefin composition formed during melt mixingTEMPO- methacrylate Loading (Molar ratio O—O:TEMPO- TEMPO- Melt IzodIzod Peroxide methacrylate) methacrylate Flow impact impact LoadingMolar ratio Loading Rate at 23° C. at −30° C. (ppm) O—O:TEMPO- (ppm)(dg/min) (J/m) (j/m) Sample ppm methacrylate ppm dg/min J/m J/mUnmodified 0 0 2.2 NB 22 Resin Peroxide 1000 0 25 83 37 Only Ex. 17 15003:1 828 21 NB 62

The blend of the polypropylene homopolymer and the polyolefin elastomerwithout either the peroxide or the compatibilizing agent, exhibitsnon-break Izod impact behavior at 23° C., but has an undesirably lowmelt flow rate. When peroxide is added to the blend, the melt flow rateincreases substantially, but the 23° C. Izod Impact Strength isundesirably reduced from a non-break to 83 J/m. Surprisingly, whenTEMPO-methacrylate is added at a 828 ppm loading, as demonstrated inExample 17, the melt flow rate remains high, the 23° C. Izod ImpactStrength exhibits non-break behavior and the −30° C. Izod impactincreases significantly. The inventive Example 17 achieves a desirablebalance of high melt flow rate and high Izod Impact Strengthperformance.

Example 18

The following examples demonstrate the production of compositionsaccording to the invention and the performance enhancements achievedthrough the incorporation of TEMPO-methacrylate (Sigma-Aldrich) intocertain polymer blends. The polymer blends consisted of a 12 dg/minpolypropylene homopolymer (LyondellBasell Pro-Fax 6301), 20 w/w % of aolefin block copolymer (INFUSE™ 9817 from The Dow Chemical Company), andoptionally an peroxide (Varox DBPH) and/or TEMPO-methacrylate. Theloadings of the peroxide and TEMPO-methacrylate are listed in Table 11with the balance of the blend being the 12 dg/min polypropylenehomopolymer.

TABLE 11 Polymer blend formulations Component Amount Polypropylenehomopolymer 500 g - Σ remaining components Olefin Block Copolymer 100.0g Primary antioxidant (Irganox ® 1010) 0.25 g Secondary antioxidant(Irgafos ® 168) 0.5 g DHT-4A 0.2 g Varox DBPH See Table 12TEMPO-methacrylate See Table 12 Irganox ® 1010 is available from BASFIrgafos ® 168 is available from BASF DHT-4A is available from KyowaChemical Industry Co., Ltd Varox DBPH is available from R. T. VanderbiltCompany

Each of the polymer blend compositions was mixed, extruded, andinjection molded according to the above procedure. The bars were thensubjected to melt flow rate and Izod impact testing described above. Theresults are reported in Table 12, below.

TABLE 12 Polymer blends using olefin block copolymers TEMPO-methacrylate Loading (Molar ratio O—O:TEMPO- TEMPO- Melt Izod IzodPeroxide methacrylate) methacrylate Flow impact impact Loading Molarratio Loading Rate at 23° C. at −30° C. (ppm) O—O:TEMPO- (ppm) (dg/min)(J/m) (J/m) Sample ppm methacrylate ppm dg/min J/m J/m Unmodified 0 0 1677 24 Resin Peroxide 500 0 49 57 17 Only Ex. 18 1000 2:1 828 40 74 26

The unmodified blend of polypropylene homopolymer and olefin blockcopolymer without additives has high Izod impact performance at 23° C.but an undesirably low melt flow rate. The addition of peroxide to thepolymer blend increases the melt flow rate to a desirable level, but theIzod impact at 23° C. and −30° C. decrease significantly. The inventiveExample 18 demonstrates that when 828 ppm of TEMPO-methacrylate is addedto the composition with 1000 ppm peroxide, the melt flow rate remains ata high level and the Izod impact at 23° C. and −30° C. increasessubstantially.

Examples 19-24

The following examples demonstrate the production of compositions andperformance enhancements achieved through the incorporation ofTEMPO-methacrylate into a high-impact heterophasic polypropylenecopolymer according to the invention. The resin used for these sampleswas an 18 MFR high-impact, heterophasic polypropylene copolymer, Pro-FaxSG702 (LyondellBasell Industries) which had approximately 25% xylenesolubles. The compositions consisted of the ingredients listed in Table13.

TABLE 13 High-impact heterophasic polypropylene copolymer ComponentAmount LyondellBasell Pro-Fax SG702 Balance Primary antioxidant(Irganox ® 1010) 500 ppm Secondary antioxidant (Irgafos ® 168) 1000 ppmCalcium stearate 400 ppm Varox DBPH See Table 14 TEMPO-methacrylate SeeTable 14 Irganox ® 1010 is available from BASF Irgafos ® 168 isavailable from BASF Varox DBPH is available from R. T. VanderbiltCompany

Each of the compositions was compounded by blending the components in aclosed container for approximately one minute. The compositions werethen melt compounded on a Prism TSE-16-TC co-rotating, fullyintermeshing, parallel, twin-screw extruder with a 16 mm screw diameterand a length/diameter ratio of 25:1. The barrel temperature of theextruder was ramped from approximately 195° C. to approximately 215° C.,and the screw speed was set at approximately 500 rpm. The extrudate (inthe form of a strand) for each polypropylene copolymer composition wascooled in a water bath and subsequently pelletized.

The pelletized compositions were then used to form bars by injectionmolding the compositions on an Arburg 40 ton injection molder having a25.4 mm diameter screw. The barrel temperature of the injection molderwas approximately 200 to 220° C., and the mold temperature wasapproximately 25° C. The resulting bars measured approximately 127 mmlong, approximately 12.7 mm wide, and approximately 3.2 mm thick. Thebars were then subjected to the impact tests described below.

The notched Charpy impact strength for the bars was measured accordingto ASTM method D6110-10. The notched Charpy impact strength was measuredat +23° C. on bars that had been conditioned at either +23° C. or −30°C. The melt flow rate (MFR) was determined according to (ASTM D1238) at230° C. with a load of 2.16 kg for polypropylene. The resulting changein melt flow rate and Charpy impact at 23° C. and −30° C. is listed inTable 14.

TABLE 14 Performance in high-impact, heterophasic polypropylenecopolymer Additive Change in Change in Loading Charpy Charpy Peroxide(Molar ratio Additive Change in impact impact Loading O—O:TEMPO LoadingMelt Flow at 23° C. at −30° C. Example (ppm) methacrylate) (ppm) Rate(%) (%) (%) Unmodified 0 0 0 0 Resin Peroxide 500 235 −55 −49 OnlyPeroxide 1000 490 −84 −61 Only Ex. 19 500 3:1 276 116 −7 13 Ex. 20 5002:1 414 72 −2 26 Ex. 21 500 1:1 827 26 4 19 Ex. 22 1000 3:1 552 170 4 14Ex. 23 1000 2:1 827 100 25 44 Ex. 24 1000 1:1 1655 18 18 30

The compositions resulting from the addition of 500 and 1,000 ppmorganic peroxide only (no compatibilizing agent) demonstrate that as theperoxide is added to the high-impact polypropylene copolymer, the meltflow rate increases significantly, but the Charpy impact at 23° C. and−30° C. decreases undesirably. The addition of TEMPO-methacrylate with500 ppm peroxide demonstrated in inventive Examples 19-21 show how themelt flow rate can be increased with minimal decreases in Charpy impactperformance at 23° C. and improved Charpy impact performance at −30° C.The use of TEMPO-methacrylate with 1000 ppm peroxide shown in inventiveexamples 22-24 demonstrate further increases in melt flow rate while theCharpy impact performance at 23° C. and −30° C. is also increased.

Examples 25-26

The following examples demonstrate the production of compositions andperformance enhancements achieved, according to the invention, throughthe incorporation of TEMPO-methacrylate into a polymer blend wherepolypropylene homopolymer is a minority component, i.e. the discretephase in the heterophasic composition. The polymer blends of the presentinvention consisted of 75 w/w % of a polyolefin elastomer (Engage™ 8842from The Dow Chemical Company), 2 dg/min polypropylene homopolymer(Total Petrochemicals 3276), 1,000 ppm of an organic peroxide (VaroxDBPH available from R.T. Vanderbilt Company) and TEMPO-methacrylate. Theloadings of the peroxide and TEMPO methacrylate are listed in Table 15,with the balance of the blend being the polyolefin elastomer andpolypropylene homopolymer. The results were compared to the heterophasicpolyolefin composition created when peroxide only was present and whenneither the peroxide nor the compatibilizing agent were present.

Each of the compositions was compounded by blending the components in aclosed container for approximately one minute. The compositions werethen melt compounded on a Prism TSE-16-TC co-rotating, fullyintermeshing, parallel, twin-screw extruder with a 16 mm screw diameterand a length/diameter ratio of 25:1. The barrel temperature of theextruder was ramped from approximately 195° C. to approximately 215° C.,and the screw speed was set at approximately 500 rpm. The extrudate (inthe form of a strand) for each polyolefin blend composition was cooledin a water bath and subsequently pelletized. The pelletized compositionswere then compression molded on a 12 ton Carver Press at a platentemperature of 230° C. and a holding pressure of approximately 6 tonsfor approximately 4 minutes into a sheet that was approximately 6″ wide,6″ long, and 0.047″ thick. ASTM Type IV dog bone specimens were then diecut from these compression-molded sheets. The tensile properties for theASTM Type IV dog bones were measured according to ASTM method D638 usingan MTS Q-Test-5 with a crosshead speed of 20.0 in/min.

TABLE 15 Performance of Polyolefin Blends Additive Loading TensilePeroxide (Molar ratio Additive Strength Tensile Loading O—O:TEMPO-Loading at Yield Modulus Example (ppm) Methacrylate) (ppm) (MPa) (MPa)Unmodified Resin — — — 3.7 12.3 Peroxide Only 1000 — — 3.7 19.7 Ex. 251000 3:1 552 4.6 26.5 Ex. 26 1000 1:1 1654 5.5 18.5

The composition comprising peroxide only (no compatibilizing agent)demonstrates that when peroxide is added to a polyolefin blendcontaining 75 w/w % polyolefin elastomer and the balance polypropylenehomopolymer, the tensile yield strength remains unchanged and thetensile modulus increases. When TEMPO-methacrylate is added to thisblend, as shown in inventive Examples 25 and 26, the tensile strength atyield increases significantly. The tensile modulus can also be increasedsignificantly when 552 ppm of TEMPO-methacrylate is combined with 1000ppm peroxide in the blend containing 75% polyolefin elastomer, asdemonstrated in Example 25.

Example 27-30 and Comparative Examples C25-C28

The following examples demonstrate unexpected improvements in theoptical properties of heterophasic impact copolymers achieved throughthe incorporation of the compatibilizing agents of the presentinvention. The inventive and comparative compounds were compounded intobatches of polypropylene copolymer compositions in accordance with thegeneral formulation set forth in Table 16.

TABLE 16 Heterophasic polypropylene copolymer formulations ComponentLoading Polypropylene copolymer (LyondellBasell Balance Pro-Fax SD375Swith approximately 19% xylene solubles) Primary antioxidant (Irganox ®1010) 500 ppm Secondary antioxidant (Irgafos ® 168) 1000 ppm Acidscavenger (calcium stearate) 800 ppm Peroxide (Varox DBPH) See Table 17Additive See Table 17 Irganox ® 1010 is available from BASF Irgafos ®168 is available from BASF Varox DBPH is available from R. T. VanderbiltCompany

Each of the heterophasic polypropylene copolymer compositions were mixedand extruded according to the above procedure. The pelletizedcompositions were then used to form disks by injection molding thecompositions on a Nissei HM7 7 ton injection molder having a 14 mmdiameter screw. The barrel temperature of the injection molder wasapproximately 215 to 230° C., and the mold temperature was approximately25° C. The resulting disks measured approximately 37 mm in diameter, and1.3 mm thick (50 mil). Clarity measurements for samples analyzed hereinwere provided according to ASTM D1003 using a haze meter such as aBYK-Gardner Haze-Gard Plus on the injection molded disks.

TABLE 17 Clarity performance Molar ratio Peroxide O—O LoadingBonds:Addi- Example Additive (ppm) tive Clarity Unmodified — 0 — 11.40Resin Peroxide — 500 — 6.16 Only Peroxide — 1000 — 5.18 Only Comp. C254-hydroxy-TEMPO 500 3 to 1 6.52 Comp. C26 4-hydroxy-TEMPO 500 2 to 16.50 Comp. C27 4-hydroxy-TEMPO 1000 3 to 1 4.58 Comp. C284-hydroxy-TEMPO 1000 2 to 1 5.28 Ex. 27 TEMPO-methacrylate 1000 3 to 124.20 Ex. 28 TEMPO-methacrylate 1000 2 to 1 23.60 Ex. 29 TEMPO-Styrene1000 3 to 1 34.40 Ex. 30 TEMPO-Styrene 1000 2 to 1 41.40

The foregoing examples demonstrate the changes in the optical propertiesof a heterophasic impact copolymer modified with the inventive nitroxidecompounds having an unsaturated bond capable of undergoing a radicaladditional reaction, relative to a nitroxide compound without anunsaturated bond. The clarity of the unmodified impact copolymer was11.4 and modification with peroxide only caused a decrease in clarity.Comparative Examples C25-C28 show that modification of the heterophasicpolypropylene copolymer with a nitroxide that does not have theunsaturated functionality decreases the clarity further. Examples 27-30show that nitroxides with unsaturated functionality increase claritysignificantly.

Without being bound to a particular theory, it is believed that thecompatibilizing agent, which has both a nitroxide functionality and anunsaturated bond capable of undergoing a radical addition reaction, iscapable of reaction with molecules in both phases of a heterophasicpolyolefin, thereby modifying the interface between the distinct phases.The modification results in a dramatic and unexpected increase in theclarity of the heterophasic polyolefin composition.

Example 31

The following example demonstrates the modification of a masterbatch andperformance enhancements achieved in a heterophasic polyolefincomposition containing the masterbatch, according to the method of thepresent invention.

Three modified masterbatch compositions were produced. ComparativeSample 31-MB (C.S. 31-MB) was made by melt compounding a polypropylenecopolymer with a peroxide as a vis-breaking agent. Samples 31A-MB and31-B MB were made by melting compounding the same polypropylenecopolymer with a peroxide as a vis-breaking agent and4-Methacryloyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl(TEMPO-Methacrylate) as a compatibilizing agent. The general formulationfor these samples is set forth in Tables 18 and 19.

TABLE 18 Modified masterbatch formulations. Component LoadingPolypropylene copolymer (LyondellBasell Balance Pro-Fax SD375S withapproximately 19% xylene solubles) Peroxide (Varox DBPH) See Table 19Compatibilizing Agent (TEMPO-Methacrylate) See Table 19

Each of the compositions listed in Table 18 was mixed, and extrudedaccording to the above procedure.

TABLE 19 Modified masterbatch compositions Sample C.S. 31-MB 31A-MB31B-MB Peroxide Loading (ppm) 1,500 5,000 10,000 Additive Loading (Molar— 1:1 1:1 ratio Additive:O—O) Additive Loading (ppm) — 8,300 16,500

Three heterophasic polymer compositions were produced by adding themodified masterbatch compositions described above to a polypropylenecopolymer. Comparative Sample 31A (C.S. 31A) was the unmodifiedpolypropylene copolymer. Comparative Sample 31B (C.S. 31B) was made bycompounding the unmodified polypropylene copolymer with ComparativeSample 31-MB (C.S. 31-MB). Sample 31A was made by compounding the sameunmodified polypropylene copolymer with Sample 31A-MB, and Sample 31Bwas made by compounding the same unmodified polypropylene copolymer withSample 31B-MB. The general formulation for these samples is set forth inTables 20 and 21.

TABLE 20 Heterophasic polypropylene copolymer formulations with modifiedmasterbatches. Component Loading Polypropylene copolymer (LyondellBasellBalance Pro-Fax SD375S with approximately 19% xylene solubles) C.S.31-MB See Table 21 31A-MB See Table 21 31B-MB See Table 21

Each of the compositions listed in Table 20 was mixed, extruded, andinjection molded according to the procedures described above. The barswere then subjected to melt flow rate and Izod impact testing asdescribed above.

TABLE 21 Performance in medium-impact, heterophasic polypropylenecopolymer Sample C.S. C.S. 31A 31B 31A 31B C.S. 31-MB (%) — 10 — —31A-MB (%) — — 10   — 31B-MB (%) — — — 10 Melt Flow Rate 20.7 22.9 23.222.6 (g/10 min) Izod impact at 80.4 80.7 86.7 90.4 23° C. (J/m)

The data set forth in Table 21 demonstrate that a modified masterbatchaccording to the invention (e.g., a modified masterbatch made by meltcompounding a heterophasic polymer with a vis-breaking agent and acompatibilizing agent) can be melt compounded into an unmodifiedheterophasic polymer, thereby significantly improving the impactstrength of the heterophasic polymer. For example, the data for C.S. 31Bshow that melt compounding the vis-broken masterbatch C.S. 31-MB intothe unmodified heterophasic polymer does not appreciably affect theimpact strength of the polymer. By way of contrast, the data for Samples31A and 31B show that melt compounding the unmodified heterophasicpolymer with the modified masterbatch compositions Sample 31A-MB andSample 31B-MB increases the impact strength of the polymer by as much as12%. This is particularly valuable because it demonstrates that improvedheterophasic polymer compositions can be produced without directlyadding the vis-breaking agent and/or compatibilizing agent to the targetheterophasic polymer. Direct addition of such additives can be difficultin certain settings, such as compounding facilities and injectionmolding facilities. However, such facilities routinely utilizemasterbatch compositions. Therefore, such facilities could readilyachieve the physical property improvements described herein through theuse of a modified masterbatch composition as described above.

Example 32

The following example demonstrates the modification of a masterbatch andperformance enhancements achieved in a heterophasic polyolefincomposition containing the masterbatch, according to the method of thepresent invention.

Three modified masterbatch compositions were produced. ComparativeSample 32-MB (C.S. 32-MB) was made by melt compounding a polypropylenehomopolymer, an ethylene/octene elastomer, and a peroxide as avis-breaking agent. Samples 32A-MB and 32B-MB were made by meltingcompounding the same polypropylene homopolymer and ethylene/octeneelastomer with a peroxide as a vis-breaking agent and4-Methacryloyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl(TEMPO-Methacrylate) as a compatibilizing agent. The general formulationfor these samples is set forth in Table 22.

TABLE 22 Modified masterbatch formulations. Component LoadingPolypropylene Homopolymer See Table 23 (LyondellBasell Pro-Fax 6301)Ethylene/Octene Elastomer See Table 23 (Dow Engage 8200) Peroxide (VaroxDBPH) See Table 23 Compatibilizing Agent See Table 23(TEMPO-Methacrylate)

Each of the compositions listed in Table 22 was mixed and extrudedaccording to the above procedures described above.

TABLE 23 Modified masterbatch compositions Sample C.S. 32-MB 32A-MB32B-MB Peroxide Loading (ppm) 3,000 9,741 18,991 Additive Loading (Molar— 1:1 1:1 ratio Additive:O—O) Additive Loading (ppm) — 16,121 31,431Polypropylene 49.9% 48.7% 47.5% Homopolymer Loading (wt %)Ethylene/Octene 49.9% 48.7% 47.5% Elastomer Loading (wt %)

Three heterophasic polymer compositions were produced by adding themodified masterbatch compositions described above to a polypropylenecopolymer. Comparative Sample 32A (C.S. 32A) was the unmodifiedpolypropylene copolymer. Comparative Sample 32B (C.S. 32B) was made bycompounding the unmodified polypropylene copolymer with ComparativeSample 32-MB (C.S. 32-MB). Sample 32A was made by compounding the sameunmodified polypropylene copolymer with Sample 32A-MB, and Sample 32Bwas made by compounding the same unmodified polypropylene copolymer withSample 32B-MB. The general formulation for these samples is set forth inTables 24 and 25.

TABLE 24 Heterophasic polypropylene copolymer formulations with modifiedmasterbatches. Component Loading Polypropylene copolymer Balance(ExxonMobil PP7414) C.S. 32-MB See Table 25 32A-MB See Table 25 32B-MBSee Table 25

Each of the compositions listed in Table 24 was mixed, extruded, andinjection molded according to the procedures described above. The barswere then subjected to melt flow rate and Izod impact testing asdescribed above.

TABLE 25 Performance in medium-impact, heterophasic polypropylenecopolymer Sample C.S. C.S. 32A 32B 32A 32B C.S. 32-MB (%) — 5  — —32A-MB (%) — — 5  — 32B-MB (%) — — — 5  Melt Flow Rate 21.2 21.2 19.419.5 (g/10 min) Izod impact at 90.5 112.54 Partial Partial 23° C. (J/m)Break Break

The data set forth in Table 25 demonstrate that a modified masterbatchaccording to the invention (e.g., a modified masterbatch made by meltcompounding a heterophasic polymer with a vis-breaking agent and acompatibilizing agent) can be melt compounded into an unmodifiedheterophasic polymer, thereby significantly improving the impactstrength of the heterophasic polymer. For example, the data for C.S. 32Bshow that melt compounding the vis-broken masterbatch C.S. 32-MB intothe unmodified heterophasic polymer does not appreciably affect theimpact strength of the polymer. By way of contrast, the data for Samples32A and 32B show that melt compounding the unmodified heterophasicpolymer with the modified masterbatch compositions Sample 32A-MB andSample 32B-MB significantly increases the impact strength of thepolymer. Indeed, the impact strength of the polymer was increased to thepoint where the part does not completely fracture during the Izod impacttest and, therefore, a value for the impact strength could not bemeasured. Such a result is particularly valuable because it demonstratesthat improved heterophasic polymer compositions can be produced withoutdirectly adding the vis-breaking agent and/or compatibilizing agent tothe target heterophasic polymer. Direct addition of such additives canbe difficult in certain settings, such as compounding facilities andinjection molding facilities. However, such facilities routinely utilizemasterbatch compositions. Therefore, such facilities could readilyachieve the physical property improvements described herein through theuse of a modified masterbatch composition as described above.

Applications

The heterophasic polyolefin composition of the present invention may beused in conventional polymer processing applications, including but notlimited to injection molding, thin-wall injection molding, single-screwcompounding, twin-screw compounding, Banbury mixing, co-kneader mixing,two-roll milling, sheet extrusion, fiber extrusion, film extrusion, pipeextrusion, profile extrusion, extrusion coating, extrusion blow molding,injection blow molding, injection stretch blow molding, compressionmolding, extrusion compression molding, compression blow forming,compression stretch blow forming, thermoforming, and rotomolding.Thermoplastic polymer articles made using the thermoplastic polymercomposition of the invention can be comprised of multiple layers, withone or any suitable number of the multiple layers containing athermoplastic polymer composition of the invention. By way of example,typical end-use products include containers, packaging, automotiveparts, bottles, expanded or foamed articles, appliance parts, closures,cups, furniture, housewares, battery cases, crates, pallets, films,sheet, fibers, pipe, and rotationally molded parts.

All references, including publications, patent applications, andpatents, cited herein are hereby incorporated by reference to the sameextent as if each reference were individually and specifically indicatedto be incorporated by reference and were set forth in its entiretyherein.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the subject matter of this application (especiallyin the context of the following claims) are to be construed to coverboth the singular and the plural, unless otherwise indicated herein orclearly contradicted by context. The terms “comprising,” “having,”“including,” and “containing” are to be construed as open-ended terms(i.e., meaning “including, but not limited to,”) unless otherwise noted.Recitation of ranges of values herein are merely intended to serve as ashorthand method of referring individually to each separate valuefalling within the range, unless otherwise indicated herein, and eachseparate value is incorporated into the specification as if it wereindividually recited herein. All methods described herein can beperformed in any suitable order unless otherwise indicated herein orotherwise clearly contradicted by context. The use of any and allexamples, or exemplary language (e.g., “such as”) provided herein, isintended merely to better illuminate the subject matter of theapplication and does not pose a limitation on the scope of the subjectmatter unless otherwise claimed. No language in the specification shouldbe construed as indicating any non-claimed element as essential to thepractice of the subject matter described herein.

Preferred embodiments of the subject matter of this application aredescribed herein, including the best mode known to the inventors forcarrying out the claimed subject matter. Variations of those preferredembodiments may become apparent to those of ordinary skill in the artupon reading the foregoing description. The inventors expect skilledartisans to employ such variations as appropriate, and the inventorsintend for the subject matter described herein to be practiced otherwisethan as specifically described herein. Accordingly, this disclosureincludes all modifications and equivalents of the subject matter recitedin the claims appended hereto as permitted by applicable law. Moreover,any combination of the above-described elements in all possiblevariations thereof is encompassed by the present disclosure unlessotherwise indicated herein or otherwise clearly contradicted by context.

What we claim is:
 1. A method of making a heterophasic polyolefinpolymer composition comprising the steps of: (a) providing a propylenepolymer phase comprising propylene polymers selected from the groupconsisting of polypropylene homopolymers and copolymers of propylene andup to 50 weight % of ethylene and/or C₄-C₁₀ α-olefins, and an ethylenepolymer phase comprising ethylene polymers selected from the groupconsisting of ethylene homopolymers and copolymers of ethylene andC₃-C₁₀ α-olefins provided that the ethylene content of the ethylenepolymer phase is at least 8 weight %, (b) providing a masterbatchcomposition comprising a compatibilizing agent and a chemical freeradical generator in a carrier resin, wherein the compatibilizing agentis selected from the group consisting of compounds that have (i) atleast one nitroxide radical or are capable of producing at least onenitroxide radical while being melt compounded with the polyolefinpolymer composition; and (ii) at least one unsaturated bond capable ofundergoing a radical addition reaction, wherein the compatibilizingagent is present in the masterbatch composition in an amount of about 1wt. % to about 80 wt. % based on the total weight of the masterbatchcomposition; and (c) mixing the propylene polymer phase, the ethylenepolymer phase and the masterbatch composition to produce free carbonradicals, whereby the compatibilizing agent reacts with propylenepolymers and ethylene polymers thereby bonding propylene polymers toethylene polymers, and whereby the propylene polymer phase and theethylene polymer phase form a heterophasic composition.
 2. The method ofclaim 1, wherein the propylene polymer phase, the ethylene polymer phaseand the masterbatch composition are mixed to produce free carbonradicals by melt compounding, and the composition is heterophasic at 25°C.
 3. The method of claim 2, wherein the propylene polymer phase is thecontinuous phase and the propylene content of the propylene polymerphase is 80 weight % or greater, and the ethylene polymer phase is thediscontinuous phase and the ethylene polymers are copolymers of ethyleneand C₃-C₁₀ α-olefins having an ethylene content of from 8 to 80 weight%.
 4. The method of claim 2, wherein the polypropylene phase and theethylene phase are provided to the mixture as a heterophasic impactcopolymer obtained by operating in at least two polymerization stages.5. The method of claim 2, wherein the nitroxide radical of thecompatibilizing agent reacts with and is bonded to a propylene polymerand the unsaturated bond reacts with and is bonded to an ethylenepolymer.
 6. The method of claim 1, wherein the discontinuous phasecomprises from 5 to 35 weight % of the heterophasic polyolefin polymercomposition, based on the weight of propylene polymers and ethylenecopolymers in the composition.
 7. The method of claim 1, wherein theethylene polymer phase has an ethylene content of from 8 to 80 weight %.8. The method of claim 1, wherein the ethylene polymer comprises from 5to 80 weight % of the heterophasic polyolefin polymer composition, basedon the total weight of propylene polymers and ethylene polymers in thecomposition.
 9. The method of claim 1, wherein the ethylene polymers areselected from the group consisting of ethylene-propylene elastomers,ethylene-butene elastomers, ethylene-hexene elastomers, ethylene-octeneelastomers, and mixtures thereof.
 10. The method of claim 1, wherein theethylene content of the heterophasic polyolefin polymer composition isfrom 5 to 60 weight %, based on the total weight of propylene polymersand ethylene polymers in the composition.
 11. The method of claim 1,wherein the propylene content of the propylene polymer phase is 80weight % or greater.
 12. The method of claim 1, wherein the ethylenepolymer phase is a discontinuous phase in the heterophasic polyolefinpolymer composition.
 13. The method of claim 1, wherein thecompatibilizing agent is mixed with the propylene polymer phase and theethylene polymer phase in step (c) in a concentration of from 10 ppm to5 weight %, based on the total weight of components used in step (c).14. The method of claim 1, wherein the unsaturated bond of thecompatibilizing agent is a double bond.
 15. The method of claim 1,wherein the compatibilizing agent is selected from the group consistingof 4-Methacryloyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl;4-Acryloyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl;4-((4-vinylbenzyl)oxy)-2,2,6,6-tetramethylpiperidine-1-oxyl;4,4′-((bicyclo[2.2.1]hept-5-ene-2,3-diylbis(oxy))bis(2,2,6,6-tetramethylpiperidin-1-oxyl);and N-tert-Butyl-α-phenylnitrone.
 16. The method of claim 1, wherein thechemical free radical generator is present in the masterbatchcomposition in an amount of about 1 wt. % to about 80 wt. % based on thetotal weight of the masterbatch composition.
 17. The method of claim 1,wherein the chemical free radical generator is an organic peroxide. 18.The method of claim 1, wherein the carrier resin is selected from thegroup consisting of polypropylene impact copolymers, polyethylenehomopolymer, linear low-density polyethylene polymers, polyolefin waxes,and mixtures thereof.